DR. W. C. MSINTOSH ON THE HAIRS OF CARCINUS MJENAS. 95 
On the projecting ledge, «, fig. 13, at the under surface and posterior part of the 
stomach are many serrated hairs of comparatively large size, and some shorter smooth 
ones with roundish points. The surface is much dotted with groups of minute points 
(tubuli). Just where the stomach merges into the intestine Fig 13. 
behind the projecting portion, there is a remarkable arrange- ) 
ment of parts. Immediately behind the projecting portion | ( 
(a, fig. 13), a ridge, b, runs straight backwards on the floor CN : ITO 7 
of the canal, and having at its termination a tongue-like pro- 4 Py: A 
cess, €. The ridge is composed of a double layer of horny ` buco 
processes arranged in an antero-posterior direction, and consisting of a dense interwoven 
series of fine pectinations or hairs. The crest of the ridge is entirely made up of these 
minute hairs, and they fringe its anterior curvature. "The parallel lines seem to be 
caused by the crossing of the minute fibres which pass between the alternate spaces 
(like two combs stuck through each other), and forming a line of junction which is well 
marked; this also corresponds to the bases of the spikes (Pl. XX. fig. 12). If the lines 
are not formed by the foregoing, there certainly do not appear to be any extraneous 
lines or fibres which run at right angles to the short perpendicular spikes ; at least, none 
are visible. The tongue-like process, ¢, posteriorly, is composed of a dense series of 
slightly serrated "hairs, which slant backwards from a horny matrix. They taper to a 
fine point, and present a granular central space. Immense numbers of cells and granules 
are always entangled amongst these hairs in the normal state of the Crab. 
On the exterior of this portion of the canal two rounded prominences exist, having 
externally an investment of parallel bands of horny tissue, running from before back- 
wards, or corresponding with the long axis of the swelling; they are smooth on the 
outer surface, but give off from the inner a vast series of tooth-like processes or pecti- 
nations. Six or eight of these teeth often converge so as to leave a wider interval 
between the ends and the succeeding groups, thus as it were marking off the long 
pectinate row into a series of shorter combs. The bands or rows, en masse, are defined 
by narrow dark lines and intervening lighter ones, the latter showing the fibrillated 
structure in virtue of their translucency. At the posterior end the rows terminate in 
beautiful pectinate structures (Pl. XX. fig. 13), which spring from one edge of a horny 
bar. These bars decrease in size towards the tip, which ends in the long and gracefully 
curved crest of processes, continuous with the other pectinations of the row. Some of 
these terminations are large and boldly marked, others smaller and fainter. The flattened 
bars of the larger ones are longitudinally striated, and appear to be composed of parallel 
fibres. Anteriorly the rows end in a smooth border, with their ends tightly bound 
together and slanted off, the pectinations at the same time becoming indistinct. Some 
of the divisions present a scalloped arrangement in every alternate row. On the field 
of the microscope besides these an elongated horny spike is often to be seen, apparently 
in connexion with this portion. : : 
Below (internal to) the horny parts above mentioned, and corresponding to their 
eurvature, is a soft, white mass composed of one vast series of hair-like fibres of a most 
beautiful silky aspect, like the finest conceivable asbestos. When put upon : slide and 
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